Aircraft nose wheel actuators may comprise a rotary damper to address shimmy in the nose wheel. The rotary damper may comprise a permanent magnet electric machine configured to create drag on the nose wheel actuator through rotation of a motor shaft and permanent magnet assembly about an electromagnetic stator.
Typically, such rotary dampers have a fixed damping coefficient. Stated differently, such rotary dampers create drag torque proportional to the speed of the motor shaft by a fixed damping coefficient. However, drag torque decreases efficiency. Rotary dampers with a fixed damping coefficient create constant drag torque, limiting the responsiveness and performance of the nose wheel actuator. Moreover, size requirements for the nose wheel actuator may increase in order to overcome the fixed drag torque created by rotary dampers having a fixed damping coefficient.